Aqueous polyurethane-urea dispersions are well known. U.S. Pat. No. 4,501,852 and the several patents referred to therein represent relevant art. These dispersions are primarily used as films, coatings or adhesives because of their good profile of properties.
An object of the invention is to provide aqueous polyurethane-urea dispersions useful for the preparation of adhesives having high softening point temperatures The softening point temperature referred to in the present context is measured in accordance with ASTM D-816 (in peel) and often used as a criterion to determine the durability of adhesives.
It was surprisingly found that the dispersion of the invention which comprise a relatively small amount of a multi-functional amine-containing chain extending agent is useful for the preparation of an adhesive which exhibits a higher softening point temperature, an excellent level of adhesion to substrates, including plasticized PVC, and a virtually unchanged tensile strength as compared to systems which include no such agent.